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Old 01-21-2011, 04:33 PM   #16
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Rafter framing code question


Well not to put too fine a point on it but he is full of sh!t and will have you waste a lot of time, material and money.

Andy.

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Old 01-21-2011, 04:40 PM   #17
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Rafter framing code question


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How can I get a bat to fit with the 10 1/4" height without touching the roof sheathing?

One of the things the inspector said was the insulation absolutely positively MUST go to the top plate. He said that is the envelope or whatever where everyone tries to 'skimp' and the heat loss in a room is. He said he will bounce me if it doesn't go to the top plate and if there is no venting.

-- Joe
That inspector is out of his mind and has no idea what he's talking about. That's his own rule. I've never heard of such a thing before. No where does anyone have to build a house or addition using at least 2x10 ceiling joists and sitting the rafters on top of them just to have bigger insulation wasting all that money in material.

Do what you have to do. The way I showed you is the way to do it. Present that to them and see what they say.
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Old 01-21-2011, 04:47 PM   #18
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Rafter framing code question


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Originally Posted by AndyGump View Post
Roof pitch has nothing to do with this, I am leery of your inspectors requirement on this.

Andy.
Andy,

Maybe I'm an idiot but.

If you have a 2x6 ceiling joist you have 5.5" of depth.

Then you have a 2x8 rafter.

At a 4 pitch or whatever it is that my house currently has, on the inside of the top plate you have about 7" total height before you crash into the roof sheathing.

If the pitch was more like a 9:12 you would gain more clearance because the angle is that much more severe.

No?

-- Joe
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Old 01-21-2011, 04:49 PM   #19
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Rafter framing code question


Hoo boy, I better watch my language here, I am not at work.

Slightly pulling back the insulation that might be in the way of air flow is and has been a perfectly accepted technique for many years.
I do not live in snow country anymore but when I did this was the norm there also.
Andy.
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Old 01-21-2011, 04:51 PM   #20
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Originally Posted by Joe Carola View Post
That inspector is out of his mind and has no idea what he's talking about. That's his own rule. I've never heard of such a thing before. No where does anyone have to build a house or addition using at least 2x10 ceiling joists and sitting the rafters on top of them just to have bigger insulation wasting all that money in material.

Do what you have to do. The way I showed you is the way to do it. Present that to them and see what they say.
Joe,

Let's step back for a second.

The span is 16'. I was going to use 2x6x16 ceiling joists to hold sheetrock and insulation.

Considering the 4 pitch roof, how would YOU frame it and fit the R38? Would you put the rafters on top of the ceiling joists on a 2nd top plate,
would you use a bigger ceiling joist?

Maybe I missed something much earlier on. I had sized the 2x6x16 ceiling joists because they are not bearing a floor or storage space, but just sheetrock and fiberglass batt.

-- Joe
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Old 01-21-2011, 04:52 PM   #21
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Rafter framing code question


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Originally Posted by anesthes View Post
Andy,

Maybe I'm an idiot but.

If you have a 2x6 ceiling joist you have 5.5" of depth.

Then you have a 2x8 rafter.

At a 4 pitch or whatever it is that my house currently has, on the inside of the top plate you have about 7" total height before you crash into the roof sheathing.

If the pitch was more like a 9:12 you would gain more clearance because the angle is that much more severe.

No?

-- Joe
Yes, Joe you're right. Problem is that it is your'e inspector is wrong about the height of the insulation going out to the plate at full height. Therefore pitch of the roof does not matter with the rest of the world. Your inspector is wrong.
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Old 01-21-2011, 04:56 PM   #22
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Rafter framing code question


Quote:
Originally Posted by anesthes View Post
Joe,

Let's step back for a second.

The span is 16'. I was going to use 2x6x16 ceiling joists to hold sheetrock and insulation.

Considering the 4 pitch roof, how would YOU frame it and fit the R38?
I don't.... no one does.


Quote:
Would you put the rafters on top of the ceiling joists on a 2nd top plate,
would you use a bigger ceiling joist?
Rafter sit on the top plate and insulation at the top gets cut off as it nears the top plate. That simple. No one frames bigger ceiling joists to accommodate insulation being full height at the plate. Again, your inspector is WRONG!!
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Old 01-21-2011, 05:04 PM   #23
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Rafter framing code question


Joe, you are by no means an idiot and Joe Carola is certainly no idiot. He is a obviously a knowledgeable and well trained framer/builder. He posts on the other forum and every one is good one. (I am such a butt kisser)
Your inspector on the other hand....?
Even if it should turn out that you absolutely must have that 10.25" on top of the double plate (ridiculous) there are other much less expensive techniques for getting you there.
All perfectly code compliant.
BTW what code are you under? IRC or UBC?
Andy
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Old 01-21-2011, 08:59 PM   #24
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"One of the things the inspector said was the insulation absolutely positively MUST go to the top plate. He said that is the envelope or whatever where everyone tries to 'skimp' and the heat loss in a room is. He said he will bounce me if it doesn't go to the top plate and if there is no venting." -------

Yes, your Inspector is correct. According to Energy Code the insulation should be full height over the exterior walls, where you need it the most from the wall cavity losing its heat from conduction and possibly convective loops to the roof framing there. It is the border of the thermal envelope = between house warm and outside air temperature; fig.4--- http://www.buildingscience.com/docum...archterm=insul

Page 2, just what you want with a S.E.s approval for the connections; http://www.nrel.gov/docs/fy00osti/26450.pdf

Many local builders are using a raised heel truss or framing similar to yours (the second diagram) to get the required R-value over the wall where it is most important.

With your rafter and 2x8 ceiling joists, you could add some foam board rips just over the wall a little to meet the requirements (site previously posted).

My State Energy Code has a sloped rafter over flat ceiling math reduction factor because of the insulation top is clipped at the slope; Attic framing is either standard or advanced. Standard
framing assumes tapering of insulation depth around the
perimeter with resultant decrease in thermal resistance. An
increased R-value is assumed in the center of the ceiling
due to the effect of piling leftover insulation. Advanced
framing assumes full and even depth of insulation
extending to the outside edge of exterior walls. Advanced
framing does not change from the default value.
U-factors for flat ceilings below vented attics with
standard framing may be modified with the following table:
Roof Pitch
U-factor for
Standard Framing
R-30 R-38
4/12 0.036 0.031


BTW, 2x6, 16o.c. span 1210, you need 2x8, 16o.c.

Gary
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Old 01-21-2011, 09:28 PM   #25
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Rafter framing code question


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Originally Posted by AndyGump View Post
Joe, you are by no means an idiot and Joe Carola is certainly no idiot. He is a obviously a knowledgeable and well trained framer/builder. He posts on the other forum and every one is good one. (I am such a butt kisser)
Your inspector on the other hand....?
Even if it should turn out that you absolutely must have that 10.25" on top of the double plate (ridiculous) there are other much less expensive techniques for getting you there.
All perfectly code compliant.
BTW what code are you under? IRC or UBC?
Andy
Hi Andy,

You guys got me confused now with GBR's last post...

Here is the exact statement on the building code:

"The provisions of the International Residential Code for One and Two Family Dwellings shall apply to the construction, alteration, movement, enlargement, replacement, repair, equipment, use and occupancy, location, removal and demolition of detached one and two-family dwellings and multiple single-family dwellings (townhouses) not more than three stories in height with a separate means of egress and their accessory structures.

Exception: Existing buildings undergoing repair, alteration or additions, and change of occupancy shall be permitted to comply with the International Existing Building Code.

The purpose of this code is to provide minimum requirements to safeguard the public safety, health and general welfare, through affordability, structural strength, means of egress facilities, stability, sanitation, light and ventilation, energy conservation and safety to life and property from fire and other hazards attributed to the built environment."


Now, I see the exception for the Existing Building Code, however I'm sure he's going to consider this an "enlargement" and keep me under the IRC.

I don't want to turn this into a debate because I'm the new guy asking for help, but basically the inspector verbally told me exactly what GBR stated in his last post. He made a big stinky deal about it.

-- Joe
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Old 01-21-2011, 09:35 PM   #26
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Rafter framing code question


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Originally Posted by GBR in WA View Post
"One of the things the inspector said was the insulation absolutely positively MUST go to the top plate. He said that is the envelope or whatever where everyone tries to 'skimp' and the heat loss in a room is. He said he will bounce me if it doesn't go to the top plate and if there is no venting." -------

Yes, your Inspector is correct. According to Energy Code the insulation should be full height over the exterior walls, where you need it the most from the wall cavity losing its heat from conduction and possibly convective loops to the roof framing there. It is the border of the thermal envelope = between house warm and outside air temperature; fig.4--- http://www.buildingscience.com/docum...archterm=insul

Page 2, just what you want with a S.E.s approval for the connections; http://www.nrel.gov/docs/fy00osti/26450.pdf

Many local builders are using a raised heel truss or framing similar to yours (the second diagram) to get the required R-value over the wall where it is most important.

With your rafter and 2x8 ceiling joists, you could add some foam board rips just over the wall a little to meet the requirements (site previously posted).

My State Energy Code has a sloped rafter over flat ceiling math reduction factor because of the insulation top is clipped at the slope; Attic framing is either standard or advanced. Standard
framing assumes tapering of insulation depth around the
perimeter with resultant decrease in thermal resistance. An
increased R-value is assumed in the center of the ceiling
due to the effect of piling leftover insulation. Advanced
framing assumes full and even depth of insulation
extending to the outside edge of exterior walls. Advanced
framing does not change from the default value.
U-factors for flat ceilings below vented attics with
standard framing may be modified with the following table:
Roof Pitch
U-factor for
Standard Framing
R-30 R-38
4/12 0.036 0.031


BTW, 2x6, 16o.c. span 1210, you need 2x8, 16o.c.

Gary
I'm going to need to read this over a couple of times. You guys unfortunately (or fortunately for you, just not me) are beyond me when it comes to some of this.

Regarding the ceiling joist span, I assumed from the table , a #1 or #2 rated 2x6 at 16" OC is good for 10psf, which is fine for sheetrock + fiberglass insulation? (picture attached)

-- Joe
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Rafter framing code question-ceiling-joists.jpg  
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Old 01-21-2011, 09:45 PM   #27
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Quote:
Originally Posted by anesthes View Post
Hi Andy,

You guys got me confused now with GBR's last post...

Here is the exact statement on the building code:

"The provisions of the International Residential Code for One and Two Family Dwellings shall apply to the construction, alteration, movement, enlargement, replacement, repair, equipment, use and occupancy, location, removal and demolition of detached one and two-family dwellings and multiple single-family dwellings (townhouses) not more than three stories in height with a separate means of egress and their accessory structures.

Exception: Existing buildings undergoing repair, alteration or additions, and change of occupancy shall be permitted to comply with the International Existing Building Code.

The purpose of this code is to provide minimum requirements to safeguard the public safety, health and general welfare, through affordability, structural strength, means of egress facilities, stability, sanitation, light and ventilation, energy conservation and safety to life and property from fire and other hazards attributed to the built environment."


Now, I see the exception for the Existing Building Code, however I'm sure he's going to consider this an "enlargement" and keep me under the IRC.

I don't want to turn this into a debate because I'm the new guy asking for help, but basically the inspector verbally told me exactly what GBR stated in his last post. He made a big stinky deal about it.

-- Joe
Joe,

What GBR is saying might be code or the way he builds where he's from, and it might be the same where you're from. Where I'm from we don't build that way nor is it code anywhere.

So, there's nothing to be confused about because you and GBR have to build one way and Andy and I don't have to build the same way. What we do works where we're from and won't work where you're from.

Now since you have to frame the way your inspector says, just draw it up with either way I showed you in the drawing as far as using hurricane ties or angled 2x4's.
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Old 01-21-2011, 09:52 PM   #28
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Rafter framing code question


Well, I was taken to school by GBR and I thank you for it.
So obviously the inspector is technically right and not much can be done about it other than to build it as he stated.
It is still IMHO a dang shame that so much material and effort has to be taken for what looks like so little gain.

Andy.
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Old 01-21-2011, 09:56 PM   #29
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Joe,

What GBR is saying might be code or the way he builds where he's from, and it might be the same where you're from. Where I'm from we don't build that way nor is it code anywhere.

So, there's nothing to be confused about because you and GBR have to build one way and Andy and I don't have to build the same way. What we do works where we're from and won't work where you're from.

Now since you have to frame the way your inspector says, just draw it up with either way I showed you in the drawing as far as using hurricane ties or angled 2x4's.
I guess I see your point. Perhaps I'm just far enough up north that everyone is picky about energy savings up here. I'm not going to argue with the building dept. because so far all my projects have gone and passed fine and I don't want to make anyone cranky. Was just wondering what was suggested.

It looks like the metal straps are the best bet, and if I go with a 2x8 ceiling joist I can run a single top plate on it which is probably better in the end, even if a 2x6 would work.

-- Joe
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Old 01-21-2011, 09:59 PM   #30
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Well, I was taken to school by GBR and I thank you for it.
So obviously the inspector is technically right and not much can be done about it other than to build it as he stated.
It is still IMHO a dang shame that so much material and effort has to be taken for what looks like so little gain.

Andy.
Agreed totally. As I was walking out the door, the building official said "This isn't about structure, this is about energy savings. Do you realize how much money you will save over the years".

It might be true, but dang the initial investment is high!

-- Joe

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